From: Garance A Drosehn <drosihn@...>
Date: 2007-02-10T08:11:16+09:00
Subject: Re: Jumping to "the next one" in something#each

------=_Part_18579_7739956.1171062672405
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

On 2/9/07, Philip Hallstrom <ruby@philip.pjkh.com> wrote:
>
> Garance wrote:
> > ...Let's say I want to have
> > something like:
> >
> > ARGV.each { |arg|
> >   case arg
> >   when "-f"
> >       ...do something with the *next* value of |arg|...
> >   end
> > }
> >
> > What I do is set some variable to remember that I'm in the middle
> > of "-f" processing, and then catch that when the code-block is
> > executed for the next value.  For example:
>
> Well, if you don't mind trashing the array you're processing you could use
> Array.shift to remove the first element and return it... then just
> re-order your loop to exit once the element returns is nil.


 That's not a general solution, though.  Consider an example of:

    filetree.added_files.keys.sort.each { |fname|
        ...whatever...
    }

I'd have to create a temp-array to hold the result from the sort step.
For that matter, I never want to *destroy* an array when I'm looping
through the values in it.  If I'm using the 'each' method, then the
array-object is never modified.

Besides, I wanted something which works for *any* routine which
takes a code-block, not just objects of type Array.  How could you
make that work for the each_pair method of Hash objects?

I was thinking there should be some "big-picture" solution possible,
one which would work for all methods which take a code-block
parameter.  That is probably too complicated a goal, but at least a
solution which would work for some large subset of those methods.

-- 
Garance Alistair Drosehn     =             drosihn@gmail.com
Senior Systems Programmer
Rensselaer Polytechnic Institute;             Troy, NY;  USA

------=_Part_18579_7739956.1171062672405--